Dowel or anchoring means

ABSTRACT

This invention relates to an anchoring arrangement comprising a plug of a two-component adhesive adapted to be received in a hole in a receiving material, said adhesive being hardenable after the intermixing of the two components and at least one component thereof being micro-encapsulated and in intimate mixture with the second component, and an anchoring rod for an arrangement rupturing said micro-capsules upon insertion into said hole.

This is a division of application Ser. No. 736,152, filed Oct. 27, 1978,and now U.S. Pat. No. 4,100,954, which is a continuation of applicationSer. No. 583,000 filed June 2, 1975, now abandoned, which in turn is acontinuation application of application Ser. No. 205,158, filed Dec. 6,1971, now likewise abandoned.

The present invention relates to a dowel or anchoring means with atwo-component adhesive which hardens after the mixing of the componentsand serves for the purpose of anchorage in the receiving material.Straddling dowels are frequently used at the present time for anchoragein brickwork, in concrete and similar foundations. Such straddlingdowels are unsuitable, however, as reinforcements for many uses thereof.For example, in the case of reinforcements on corners of brickwork bymeans of straddling dowels, there arises the danger that masonry willchip off because of the straddling forces. Light-weight buildingmaterials are being employed to an increasing extent in the buildingarts, such as for example gas concrete, aeroconcrete, Ytong buildingblocks (building blocks or bricks from slag or clinker material), andsimilar soft materials. The high straddling forces arising in the caseof straddling dowels exceed the mechanical or structural resistance ofsuch materials, and the result thus will be a loosening and breakingaway of the anchoring means, or other damage. In addition, the torsionalstability of the known dowels in the materials mentioned hereinabove isoften insufficient.

Already known in the art is an adhesive dowel with the aid of which thedisadvantages outlined above are intended to be obviated. This adhesivedowel has a two-component adhesive. Each component of this adhesive isenclosed within a glass container. One glass container encloses theother glass container. This prior art adhesive dowel is mounted or putin place as follows: A hole is drilled initially in the foundation. Thesmall glass tube is then inserted into the hole. Thereafter the dowel oran anchoring means is driven into the borehole by means of a percussiondrill. At that time the glass containers are destroyed and the adhesivecomponents, being released as a result, are intermixed. The twocomponents of the adhesive react with each other, and the adhesivehardens fully.

This prior art adhesive dowel has numerous disadvantages and drawbacks,namely:

It requires two small glass tubes which are provided within each otherin each case and each of which is filled with one component of theadhesive. The expenditure involved in making these glass tubes isrelatively high. The small glass tubes break easily, which is a distinctdisadvantage particularly in the building industry. The glass fragmentsof an unintentionally broken glass tube bring about the danger ofinjuries, and the adhesive which runs out may cause ugly soiling.Moreover, skin cauterizations may be the result when operators come intocontact with the running adhesive.

In order to make a good adhesive effect possible, the two components ofthe adhesive must be well intermixed while the dowel or anchoring meansis inserted.

A sufficiently good and uniform mixing upon which the correct hardeningof the adhesive depends is not always assured in the prior art adhesivedowel.

It is the object of the present invention to eliminate the disadvantagesand drawbacks of the prior art devices.

In a device of the type referred to hereinabove, this object isobtained--in accordance with the present invention--by virtue of thefact that at least one adhesive component is micro-encapsulated, andthat the micro-capsules are in an intimate mixture with the secondcomponent.

The present invention makes use of the micro-encapsulation technique.This is a new physico-chemical process for enclosing very small amountsof liquids and solid materials, for example by preserving. The walls ofthe capsule can be destroyed by mechanical influence, for example bypressure, whereupon the content of the capsules will be released. Thefact that at least one component of a two-component adhesive ismicro-encapsulated assures that no reaction with the likewise presentsecond component will take place even though both of thecomponents--separated from each other only by the capsule walls--arewell intermixed. As a result, the adhesive being prepared for thereaction can be stored for almost an indefinite period of time. Onlyafter the capsule walls have been destroyed will the two adhesivecomponents come into contact with each other; a reactive mixture of thetwo adhesive components is produced, and the adhesive will harden fully.

The present invention affords numerous advantages. The adhesive which isprepared for the reaction is present in dry form. No glass tubes such asthose referred to above in connection with the prior art adhesive dowelare required, and the problems pertaining to the latter are accordinglyeliminated. A good hardening of the adhesive once the capsule walls havebeen broken open is effectively assured by virtue of the fact that thetwo components in the non-reactive condition thereof are separated fromeach other only by the capsule walls and yet are mixed well with eachother. If some capsules should be destroyed, due to improper handling,before the time for the application thereof, the only result can be areaction of the polymer material having been liberated. The function ofthe dowel, however, is not impaired thereby because during theapplication, the remaining capsules will react after having been brokenopen. While the prior art adhesive dowel described above can bepractically made only in greater dimensions, the dowel or anchoringmeans proposed by the present invention also may be made very small.

A two-component adhesive according to the present invention may have,for example, as a first component a slowly reactive, medium-reactive orhighly reactive unsaturated polyester resin with an accelerator, forexample diethyl aniline, and, as a second component an organic peroxidein either solid or liquid form. If one component is present in solidform, it can be diluted in a suitable solvent, for example phthalate,for purposes of encapsulation.

The micro-capsules are advantageously linked with each other by means ofa binding agent. It is possible to connect the micro-capsules in thesame manner also with a further part of the dowel or anchoring means. Itis possible to use as a binding agent, for example, alkydresins, vinylcompounds, acrylic resins, latex compounds, gelatin, and similarsubstances.

A liquid component of the adhesive is advantageously micro-encapsulated.The other component can in that case be a powder which adheres to themicro-capsules on the outside thereof. Thus, each individual capsulerepresents a complete adhesive system.

According to another embodiment of the present invention, bothcomponents of the adhesive are micro-encapsulated. Achieved as a resultis an even higher guarantee against undesired, premature reactions ofthe two components with each other.

In the dowel or anchoring means according to the present invention, onlya limited space is available for the adhesive. The adhesive effect,however, improves progressively the more adhesive is accommodated withinthis space. It is therefore desirable to achieve as high a bulk weightas possible per unit of volume. It has been found in this connection tobe advantageous not to use micro-capsules having a uniform diameter, butrather capsules with different diameters, so that the diameter thereofis within a specific spectrum. A diameter spectrum of the micro-capsulesof between 300 and 1200 microns has been found to be particularlyadvantageous.

The expenditures for the dowel or anchoring means according to thepresent invention can be further reduced by adding, if desired, a filleragent to the adhesive substance. This addition can be so made that thefiller is disposed either within the capsules or outside of them. Quartzsand or quartz powder with varying fine grain sizes are particularlyfavorable fillers. Other fillers, however, also may be used instead.

It may be advantageous to provide the micro-encapsulated two-componentadhesive as a body separate from other parts--if they exist--of thedowel or anchoring means according to the present invention. In thatcase the adhesive, at least one component of which ismicro-encapsulated, is suitably made according to the extrusion processin the form of, for example, a cylindrical strand or a cylindrical tube.In order to obtain an anchoring effect, such an adhesive body, forexample, may be inserted in a mounting hole having the same diameter asthat of the adhesive body. Inserted into the adhesive body thereafter,for example, is an anchoring means having a conical tip and whosediameter is smaller than the outside diameter of the adhesive body. Whenthe anchoring means is inserted into the adhesive body, the walls of themicro-capsules are destroyed and the adhesive hardens. The two-componentadhesive, at least one component of which is micro-encapsulated, ofcourse also can be extruded directly into the borehole. The adhesivebody also may be enclosed with a porous sheathing, for example a gauze,in order to protect the outwardly positioned micro-capsules againstmechanical damage and for the purpose of achieving a mechanicalreinforcement and stabilization. It is advantageous to extrude themicro-encapsulated two-component adhesive, which is made into a pastewith a suitable readily volatile liquid and, if desired, a thixotropicagent, directly into a prepared mounting hole in a mounting foundation,for example, by means of a hand-operated instrument. The extrudedcapsule paste solidifies once the pasting liquid has volatilized, and itis then possible to screw thereinto, for example, a fastening screwwhereby the walls of the micro-capsules are destroyed and after whichthe adhesive hardens.

The adhesive advantageously may be connected with flexible porouscarrier substances. This assures a particularly firm and rigid adhesivebody to which a filler, namely the carrier substance, is added at thesame time. The carrier substance must be porous so that the componentsof the adhesive are adapted, after destruction of the micro-capsules, toeasily penetrate therethrough and establish a connection not only withthe wall of the mounting hole but also with the anchoring device. Themicro-capsules are protected particularly effectively againstundesirable mechanical stresses when they are arranged between thelayers of a cylinder from two layers of a flat carrier substance.

Preferred as a carrier substance is a fibrous mixture, a fleece, or agauze material made from glass fibers. Other carrier substances, such aspaper, for example, or also other tissues or fleeces from other fibersmay be equally employed.

The carrier substance is advantageously a flat structure which is coatedat least on one side thereof with the two-component adhesive and rolledin several layers to form a cylinder or a hollow cylinder. Such a dowel,which must be made in a suitable length, can be used directly, andwithout requiring further parts, for anchoring purposes together withordinary wood screws or self-tapping screws, in the manner of the knownplastic straddling dowels. In order to make an anchoring with this typeof dowel, a mounting hole is drilled into the receiving material whichhole has approximately the dowel diameter and into which the dowel ofthe construction or configuration described herein is inserted. Toobtain the anchorage or fastening, an ordinary wood screw is thenscrewed into the dowel. Due to the forces arising at the time of thethreading action, the walls of the micro-capsules are destroyed and thetwo-component adhesive hardens. A dowel of the construction referred tohereinabove last is made, for example, in that strips of supportingmaterial being layered on one side thereof with the micro-encapsulatedtwo-component adhesive and having a width equal to the desired dowellength are wound on to mandrels until the desired dowel diameter hasbeen achieved. Wider sheets of supporting material also may be used,however, for the winding operation. In the latter case it is necessaryto cut the rolled or wound body into suitable partial lengths. This typeof dowel is thus particularly simple to make with little expenditure.Another advantage of the dowel having this particular construction isthat, immediately after a screw has been provided therein, clampingforces exist which are not so significant as to be capable of damagingthe receiving material while, however, being sufficient to initiallyassure a supporting effect which is very advantageous in actualpractice. The nominal supporting power or carrying capacity of thisdowel is thereafter obtained following the hardening of thetwo-component adhesive.

Advantageously, at least one supporting element of the dowel oranchoring means is provided with the two-component adhesive, and thewalls of the microcapsules can be destroyed by connecting a mountingelement with the first element. Mounting elements which can be connectedwith the supporting element must carry the adhesive body at a point onwhich it is mechanically stressed until is is destroyed, during theattachment of the mounting element to the supporting element.

According to another embodiment of the present invention, the supportingelement is a hollow cylinder which is closed at one end thereof and inwhich the two-component adhesive is disposed; the wall of this hollowcylinder comprises numerous radially-extending perforations and amounting element is adapted to be driven into the open end of thecylinder. When the mounting element is driven thereinto, themicro-capsules are partially destroyed due to the pressure arising atthe time of such driving, and partially also at the time of passagethrough the narrow perforations in the cylinder wall. These perforationsof course must be made so small that the destruction of all themicro-capsules is assured.

When a screw is intended to be connected with the supporting element,the anchoring element is equipped at the open end thereof with aninternal thread.

According to yet another embodiment of the present invention, thetwo-component adhesive is rigidly disposed on the outside of asupporting element, and the dowel or anchoring means comprises anothersleeve or shell which can be slid over the supporting element with theensuing destruction of the walls of the micro-capsules. One end face ofthe cylinder wall of the sleeve or shell is advantageously provided as ascraping cone for scraping the adhesive off of the supporting elementduring the destruction of the micro-capsule walls. There still willremain a sufficient amount of adhesive between the sleeve or shell andthe supporting element to assure the connection between these twoelements. In order that his connection becomes even stronger, thesupporting element has a flange at the end face thereof with which it isinitially inserted into the mounting hole. This flange transfers theextracting forces arising at the supporting element to the sleeve orshell being firmly cemented within the mounting hole.

The supporting element advantageously has a thread for a mountingelement. If an internal thread is provided for, a screw bolt may beconnected with the supporting element. If the supporting element isequipped with an external thread at a projecting part, a nut may bescrewed thereupon.

According to a still further embodiment of the present invention, thesupporting element is conically provided and carries the adhesive bodyon its conical exterior. For such a dowel or anchoring means it isnecessary to drill a conical hole into the receiving material. The dowelor anchoring means is then either threaded or driven into this mountinghole, at which time the walls of the micro-capsules are destroyed andthe adhesive hardens.

In order to enhance the adhesive connection with the fastening ormounting foundation, the outer surface of the supporting element may beuneven. It can be provided, for instance, with projections, a thread, orwith grooves extending transversely to the longitudinal extension anddirection of the supporting element.

The supporting element is suitably of metal. Other materials, however,such as, for example, plastic, or a combination of these materials, maybe equally used therefor.

The present invention will now be further described hereinafter on thebasis of several embodiments thereof and taken in connection with theaccompanying drawings, wherein:

FIG. 1 illustrates an adhesive dowel for a fastening screw;

FIGS. 2a, 2b and 2c illustrate different steps in the assembly ofanother embodiment of an adhesive dowel upon which a nut may bethreaded;

FIG. 3 illustrates the embodiment or construction of an adhesive dowelsimilar to that shown in FIGS. 2a through 2c, but which comprises aninternal thread instead of a projection with an external thread;

FIG. 4 illustrates an embodiment or construction for an adhesiveanchoring means;

FIG. 5 illustrates a further embodiment or construction of an adhesivedowel which may be used either singly or in combination with theadhesive anchoring means according to FIG. 4;

FIGS. 6 and 7 illustrates yet another embodiment or construction of adowel as proposed by the present invention, and

FIG. 8 illustrates schematically an apparatus for making a dowel asshown in FIGS. 6 and 7.

The dowel according to FIG. 1 which has been identified with referencenumeral 1 in its entirety has a cylindrical sleeve or shell 2 as asupporting element. One end of the cylindrical sleeve or shell 2 isclosed with an end face 3.

The inside of the cylindrical shell or sleeve 2 is filled over thelength L₁ with a two-component adhesive 4 and both of the components ofthe latter are micro-encapsulated. Apertures 5 are present in thecylindrical wall of the cylindrical sleeve or shell 2. The latter has atits open end a screw thread 6. In order to mount the dowel 1, a mountinghole 7 is drilled into a receiving material 8, for example a brick wall.Thereafter the sleeve or shell 2 with the adhesive 4 is pushed orinserted into the fastening hole 7. Thereupon a fastening screw 9, whichis provided with a screw thread 6a only at the rear portion of the shankthereof over a length L₂, is first inserted into the dowel 1 and thentightened therein. At that time the micro-encapsulated two-componentadhesive 4 is compressed and forced through the apertures 5 in the wallof the cylindrical sleeve 2. As a result, the walls of themicro-capsules are ruptured and the two components of the adhesive reactwith each other, with the ensuing hardening of the adhesive.

Reference is now had to FIGS. 2a to 2c. FIG. 2a shows an adhesiveanchoring means or stay 10 which has a shank 11, the latter carrying aflange 12 at one end thereof. At the opposite end thereof the shank 11has an external thread 13. The shank 11 is layered over the entirelength thereof with the micro-encapsulated two-component adhesive 14.Further provided for the mounting of the adhesive anchoring means 10 isa cylindrical sleeve or shell 14a having the same length as the shank11. At one end 15 thereof, the sleeve or shell 14a is conically tapered.

In order to mount the adhesive anchoring means or stay, a fastening hole7 is here again first drilled into the receiving material 8. Then theadhesive anchoring means 10 together with the flange 12 at the head isinserted into the fastening hole. By way of the shank 11 the sleeve 14awith its conically tapered end 15 is next inserted. The last part of theway the sleeve 14a is driven in, as is apparent from FIG. 2c. When thesleeve 14a is slid in, the micro-encapsulated two-component adhesive 14is at least partially pushed off of the shank 11 while the capsule wallsare being ruptured, forced into the space between the fastening hole 7and the outer wall of the sleeve 14a, and hardens. Thereafter, anydesired part or element can be secured to the adhesive anchoring means10 with the aid of a nut which is threaded on the external thread 13.

FIG. 3 illustrates an adhesive anchoring means 10 which is similar tothat shown in FIGS. 2a-2c, but which merely has an internal thread 16instead of the external thread 13.

FIG. 4 illustrates a tie bar 17 with a shank 18 carrying a thread 18a.Disposed at one end of the shank 18 is a cylindrical part 19 having agreater diameter than that of the shank 18 which ends conically at theend 20 thereof facing away from the shank 18.

For purposes of connecting the tie rod 17 with a receiving material, anadhesive body 21 with micro-encapsulated two-component adhesive isprovided.

To mount the tie rod 17, a fastening hole 7 is drilled into a receivingmaterial 8. The adhesive body 21 is then inserted into this fasteninghole 7. Inserted next into the hole is the tie rod 17 with its conicalend 20 first. The diameter of the fastening hole is expediently chosenonly slightly larger than the diameter of the cylindrical part 19 of thetie rod. When the tie rod 17 is inserted into the fastening hole 7, thewalls of the micro-capsules are ruptured and forced through theinterstice between the cylindrical part 19 and the wall of the borehole.The adhesive will then harden. The insertion of the tie rod 17 into thefastening hole 7 is effected expediently with the aid of a percussiondrill whose percussion rotating attachment has been indicated at 31 andwhich is in operative engagement with the thread 18a at the shank 18.

FIG. 5 illustrates a further embodiment of the adhesive body 21 which,in this case, is provided as an extruded cylinder 21a. The adhesivecomponents, at least one of which is micro-encapsulated, are connectedwith each other by means of binders and also may be provided with afiller.

With a suitable matching or coordination of the dimensions of thefastening or mounting hole within the receiving material of the adhesivebody and of the fastening screw, such as an ordinary wood screw, theadhesive body 21a also may be directly used as the dowel. For thatpurpose it also may be provided as a hollow cylinder.

FIGS. 6 and 7 illustrate another embodiment of an adhesive dowel. Thisdowel consists of a band 22 from a flexible porous material, such as aglass fiber fleece, for example. The band 22 is coated on both sidesthereof with a micro-encapsulated two-component adhesive 23, which willadhere thereto. The band 22 carrying the micro-encapsulated adhesive 23is wound to form a hollow cylinder, such as is apparent from FIG. 7. Thevarious layers of the hollow cylinder adhere to each other. Thisparticular dowel then may be directly employed with fastening screws,for example with wood or with self-tapping screws, in the manner ofconventional plastic straddling dowels. The thickness of the adhesivelayer 23 is suitably selected. This dowel may be made approximately inthe manner apparent from FIG. 8.

Two bands 25 and 26 which are coated on the upper side thereof with amicro-encapsulated two-component adhesive which adheres thereto arewound, in a superimposed manner with respect to each other, on a mandrel24 which rotates in the direction of the arrow, so as to form acylindrical tube 27. During the winding operation, the cylindrical tubeis continuously advanced in the direction of the arrow 28. If a greaterwall thickness of the tube is desired, more than two bands may be usedfor the winding operation.

The tube is cut into suitable sections 30 by a cutting device 29, andthese sections then may be used as dowels.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

What is claimed is:
 1. An arrangement for anchoring objects to supportstructures, especially support structures of light-weight buildingmaterials, comprising an anchoring rod insertable with clearance into ananchoring hole in a support structure, said anchoring rod comprising anelongated stem and a flange of a diameter only slightly smaller thanthat of said anchoring hole at a leading end of said stem; and means forsecuring said anchoring rod in said anchoring hole consisting of a plugof a hardenable substance in said anchoring hole in the path of saidanchoring rod and having two intermixed components at least one of whichis encapsulated in microcapsules, so that the substance is squeezed bysaid anchoring rod during insertion thereof into said anchoring holewith concomitant rupturing of the microcapsules and resulting formationof an intimate mixture of said components which are displaced by saidanchoring rod during advance thereof into the clearance between theanchoring rod and the anchoring hole to subsequently harden therein,said plug being a hollow cylindrical plug having an outer diametersubstantially equal to that of said anchoring hole and an inner diametersmaller than that of said flange, said plug comprising a flexible porouscarrier sheet coated at least on one side therof with said hardenablesubstance and wound in several layers to form said hollow cylinder, saidanchoring rod being secured in said anchoring hole exclusively by saidsubstance after the latter has hardened.
 2. An arrangement as defined inclaim 1, wherein said porous carrier sheet comprises a mixture offibers.
 3. An arrangement as defined in claim 2, wherein said fibers areglass fibers.